A readily available colorimetric and near-infrared fluorescent turn-on probe for detection of carbon monoxide in living cells and animals

Since carbon monoxide (CO) was recognized as an important gasotransmitter, great interest has been given to develop probes for detection of this gas molecule in living systems. While several fluorescent probes have been developed very recently for imaging CO in living cells, probes for in vivo detection of CO have not yet been reported. Herein, we report a new NIR fluorescent CO probe that can be used for detection of CO both in vitro and in vivo. This probe works in almost wholly aqueous solution under mild conditions and shows high selectivity and sensitivity for CO in the presence of Pd2+, giving rapid (within few minutes) and distinct colorimetric and near-infrared (NIR) fluorescent turn-on signal changes with a detection limit as low as 3.2 nM. Moreover, we also show that this probe has low cytotoxicity and can be conveniently used to image CO in both living cells and animals.